A: No, just charge it whenever you want. Li-Ion batteries, the type used in laptops and mobile phones, have no charge memory. You can use it down to 39% (just an example....) and charge it without discharging completely. It's safe, and actually, it's better for your battery life if you don't do a full charge-discharge before you charge it. Only do a full charge and discharge once every 4-6 weeks, or after 25-30 times if you use your laptop on battery power often. The battery life you get from it will stay high for longer, and the battery itself will last longer.

When it has fully charged on my desk should I unplug and let the battery discharge as I use or is it ok to just leave it plugged in?

My colleague says I should unplug. I think there's logic in the laptop/battery that prevents damage when it's reached the fully charged state.

Who's right?

A: No, just leave it plugged in if you want. Your laptop's battery will drain a bit if you leave it plugged in, but it won't really go into recharge mode if the battery is 96% and above. If you drain the battery until 89% or so, and plug it back in, the charge indicator will go from green to amber/orange, and will charge until it reaches 100% again. After that, it'll continually trickle some power into the laptop so that the battery is always topped up, but again, it won't really recharge until the battery life is 95% and below.

Well its been proven that they can be just fine after many recharging cylces... Its ok to leave it pluged in the Newer batterys have been made to not allow it to "over charge" the batt... Now if you have a lead-acid Batt you need to upgrade ... But you sould be good, the batterys will not be affect that much ether way...

I have several laptops, and in the interest of science I left one battery in (while they where plugged in to the mains) and one out. After 12 months, the one with the battery constantly in has completely messed up, and holds only 25 MINS charge! The other one was used every so often, and has the full 2 hour life (the same as when I got it).

So.. I say, unplug battery when on the mains for extended periods of times.

interesting... i leave my PB plugged in at home almost for a week straight, and then use it off the battery once a week.

i might take the battery out when i've got it plugged in for extended periods. but then again, with the battery in, it's like a built in UPS. handy in a blackout. or maybe i should just start using my laptop like a laptop. now that i've got AirPort setup, i dont' know why i'm still sitting at my desk the whole time?

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